Intraluminal medical delivery systems may be configured to deliver a self-expanding device, such as a stent, prosthetic valve device, or other implantable article, inside a patient's body. Medical delivery systems may also be configured for rapid insertion and removal. Such delivery systems have been described in the United States Provisional Patent Application filed on Apr. 20, 2005 and having an application Ser. No. 60/673,199 and client reference number PA-5598-PRV, the disclosure of which is incorporated in its entirety.
By way of background, stents are configured to be implanted into body vessels or passageways in order to reinforce, support, repair, or otherwise enhance the performance of the passageway. The term “passageway” is understood to be any vessel, lumen, channel, flow passage, duct, chamber, opening, bore, orifice, or cavity for the conveyance, regulation, flow, or movement of bodily fluids and/or gases. As an example, stents have been used in the passageways of the aorta, arteries, bile duct, blood vessels, bronchiole, capillaries, esophagus, fallopian tubes, heart, intestines, trachea, ureter, urethra, veins, and other locations (collectively, “vessel”) in the body.
One type of stent is self-expanding. For a self-expanding stent, the stent is resiliently compressed into a collapsed first, smaller diameter, carried by the delivery system, and due to its construction and material properties, the stent expands to its second, larger diameter upon deployment. In its expanded configuration, the stent exhibits sufficient stiffness so that it will remain substantially expanded and exert a radially outward force in the vessel passageway on an interior surface of the vessel. One particularly useful self-expanding stent is the Z-stent, introduced by Cook Incorporated, due to its ease of manufacturing, high radial force, and self-expanding properties. Examples of the Z-stent are found in U.S. Pat. Nos. 4,580,568; 5,035,706; 5,282,824; 5,507,771; and 5,720,776, the disclosures of which are incorporated in their entirety.
A wire guide can be used to place a self-expanding stent delivery system into a vessel passageway percutaneously. The typical wire guide has proximal and distal ends. A physician inserts the distal end into the vessel passageway, advances, and maneuvers the wire guide until the distal end reaches its desired position within the vessel passageway.
Many delivery systems employ a tubular catheter, sheath, cannula, introducer, or other medical delivery device (individually and collectively, “catheter”) having first and second ends and comprising a lumen for receiving the wire guide. Optionally, these delivery systems may fit a working channel within an endoscope or an external accessory channel device used with an endoscope.
Generally stated, these delivery systems may fall into one of two categories. The first category to be used, and consequently the first to be discussed below, is commonly referred to as an “over-the-wire” system. The other category of delivery system is sometimes referred to as a “rapid exchange” catheter.
In the “over-the-wire” catheter delivery system, a physician places the catheter over the wire guide, with the wire guide being received into a lumen that extends the entire length of the catheter. In this over-the-wire type of delivery system, the wire guide may be back-loaded or front-loaded into the catheter. In back-loading an over-the-wire catheter delivery system, the physician inserts a distal portion of the catheter over the proximal end of the wire guide. In front-loading an over-the-wire catheter delivery system, the physician inserts the distal end of the wire guide into the catheter's lumen at or near the catheter's proximal end. The back-loading technique is more common when the physician has already placed the wire guide into the patient. In either case of front-loading or back-loading an over-the-wire catheter delivery system, the proximal and distal portions of the catheter will generally envelop the length of the wire guide that lies between the catheter first and second ends. While the wire guide is held stationary, the physician may maneuver the catheter through the vessel passageway to a part of the target site at which the physician is performing or intends to perform a treatment, diagnostic, or other medical procedure.
Unlike the over-the-wire system, where the wire guide lies within the catheter lumen and extends substantially the entire length of the catheter, in a “rapid exchange” catheter delivery system, by contrast, the wire guide occupies a catheter lumen extending through only a distal segment of the catheter. The so-called rapid exchange system comprises a proximal end, an elongate flexible middle section delivery device, and a distal end that is generally tubular.
The distal end, in general, comprises an inner guide channel member sized to fit slidably within an outer guide channel member that is substantially axially slideable relative to the inner member. The outer guide channel member and inner guide channel member further have entry and exit ports defining channels configured to receive a wire guide. A port includes any structure that functions as a portal, port, passage, passageway, opening, hole, cutout, orifice, or aperture, while a guide channel is understood to be any passageway, lumen, channel, flow passage, duct, chamber, opening, bore, orifice, aperture, or cavity that facilitates the passage, conveyance, ventilation, flow, movement, blockage, evacuation, or regulation of fluids or gases or the passage of a diagnostic, monitoring, scope, other instrument, or more particularly a catheter or wire guide.
A wire guide may extend from the outer and inner member entry ports, through the outer and inner member guide channels, and exit the distal end at or near a breech position opening located at or near a transition region where the guide channels and exit ports are approximately aligned relatively coaxially to facilitate a smooth transition of the wire guide. Furthermore, the outer guide channel member has a slightly stepped profile, whereby the outer member comprises a first outer diameter and a second smaller outer diameter proximal to the first outer diameter and located at or near the transition region.
The distal end also has a self-expanding deployment device mounting region (e.g., a stent mounting region) positioned intermediate the inner guide channel member entry and exit ports for releasably securing a stent. At the stent mounting region, a stent is releasably positioned axially intermediate distal and proximal restraint markers and sandwiched transversely (i.e., compressed) between the outside surface of the inner guide channel member and the inside surface of an outer guide channel member.
Turning to the proximal end of the rapid exchange delivery system, the proximal end, in general, comprises a handle portion. The handle portion has a handle that the physician grips and a pusher stylet that passes through the handle. The pusher stylet is in communication with—directly or indirectly through intervening parts—the inner guide channel member at the distal end. Meanwhile, the handle is in communication with—directly or indirectly through intervening parts—the outer guide channel member at the distal end. Holding the pusher stylet relatively still while actuating the handle thereby keeps the stent mounting region at the inner guide channel member properly positioned at the desired deployment site. At the same time, proximally retracting the handle results in a corresponding proximal movement of the outer guide channel member relative to the inner guide channel member thereby exposing and, ultimately, deploying the self-expanding stent from the stent mounting region. At times, a physician may need to deploy a second self-expanding stent by withdrawing the system from the proximal end of the wire guide and then reloading the catheter onto the wire guide with an additional stent, or by replacing the delivery system with a catheter or different medical device.
The delivery system in the rapid exchange delivery system further comprises an elongate longitudinal flexible middle section delivery device extending intermediate the proximal end and the distal end. The middle section delivery device comprises an outer sheath and an inner compression member having first and second ends associated with the distal end and proximal end, respectively.
More particularly, the outer sheath distal end may be coterminous with or, if separate from, may be associated with (e.g., joined or connected directly or indirectly) the distal end outer guide channel member at or near the transition region, while the outer sheath proximal end is associated with the handle. The inner compression member first end is associated with the distal end inner guide channel member at or near the transition region, while the inner compression member second end is associated with the pusher stylet at the proximal end. Therefore, the outer guide channel member of the distal end may move axially (as described above) and independently relative to an approximately stationary inner guide channel member of the distal end and, thereby, deploy the stent.
Traditional ways of associating an outer sheath distal end and an outer guide channel member second end at a transition region include the use of glue, adhesives, and the like (collectively, “glue”). For example, a subassembly (or insert) may be adhered at a proximal end to the outer sheath and adhered at a distal end to the outer guide channel member. One must choose the right glue, however, to join dissimilar materials, and the glue must cure, thereby increasing the total processing (fixture) time in the application and assembly of the device.
Moreover, the glued portions of a subassembly may vary in strength and integrity depending on the congruity of the mating surfaces. In addition, if the subassembly material is not properly selected, the transition region may be too rigid, reducing the ability of the delivery system to navigate a tortuous path within the vessel passageway, or it may be too weak, and thus prone to kinking.
It would be desirable to provide an insert for joining sheaths in an intraluminal device delivery system that may be rapidly assembled, provide a secure coupling, and have a maneuvability and kink resistance which is similar to those of the sheaths.